Beverage dispensing machines generally are intended to expel or deliver a beverage or beverage concentrate in a reasonably sanitary manner. Generally, beverage dispensing machines require a mechanism to pump or expel the beverage, a nozzle or interface between the beverage and the external environment, and a method or device to control the flow rate of the beverage.
Typically beverage dispensing machines expel the beverage or beverage concentrate either by using a diaphragm pump, a peristaltic pump, a direct gas pump, or by using gravity to cause the liquid to flow out of the ingredient storage container.
A diaphragm pump uses a movable diaphragm to directly push the beverage out of the storage container. A disadvantage of this type of prior art pump is that the ingredient being pumped comes in direct contact with internal parts of the diaphragm pump. Such contact increases the risk of bacterial contamination and makes the system difficult to clean and sanitize.
A peristaltic pump, on the other hand, comprises a rotating apparatus which periodically squeezes a substance through a flexible tube. One disadvantage with using a peristaltic pump is that whenever new product is loaded into the system, the operator must mate the disposable tube to the permanent peristaltic pump tube. Another disadvantage of the peristaltic pump is that the permanent tube comes in contact with the product and must be washed out regularly to maintain appropriate levels of sanitation.
Another way to expel a beverage is with a compressed gas system as is done, for example, with a beer keg. In a compressed gas system, a compressed gas is introduced into the liquid container, the pressure of which expels the liquid. A major drawback with this method, however, when applied to edible or organic products, is that the propellant gas coming in direct contact with the product makes the product more prone to spoilage or environmental contamination.
In a gravity flow system, the weight of the ingredient is used to provide the force to expel the product. One disadvantage of the gravity flow system, however, is that the flow rate of the dispensed liquid is dependent on the head pressure of the ingredients. As the ingredient empties, the head pressure decreases, which results in a reduction of flow rate. A second disadvantage of the gravity flow system is that more viscous ingredients will flow at unacceptably slow flow rates.
In order to maintain a sanitary environment to dispense beverages and other liquid food items, attention must be given to the dispensing and closure nozzle, the designs of which can vary widely, because the nozzle provides an interface between the liquid and the external environment. This is particularly an issue with low-acid products that are high in nutrients, which are particularly prone to bacterial growth.
In the bag-in-box industry, for example, it is common for a bag to have a long tube with a closed tip used for transportation and storage. When the beverage is ready for dispensing, the tube is placed through a pinch valve mechanism and the end of the tube is cut, allowing the product to be dispensed when the pinch valve is open. One disadvantage with this method is that once the tube is cut, it cannot be resealed without resorting to a mechanical means to pinch the tube shut. Another disadvantage with this method is that the end of the tube is exposed to the environment, resulting in the possibility of contamination and the potential for the ingredient to dry in the tube.
Another disadvantage is that, because the tube must be physically cut, the cutting device also requires cleaning and sanitizing. In addition, the cutting device can be lost, dulled, misused and left unclean. The tube can also be incorrectly cut, whether cut at an angle, jagged, or cut too high or too low on the tube.
Another dispensing and closure nozzle technique employed in the bag-in-box industry is to use a bag cap that mates to a receiving fitment that is connected to a larger dispensing system. A disadvantage with this method is that it requires at least two external pieces. Another disadvantage with this method is that these external pieces and the associated pumping mechanism need to be cleaned regularly or replaced if good sanitation is to be maintained.
Another issue with prior art beverage dispensing machines involves automatic product changeover for beverage dispensing systems that employ a plurality of product storage containers. Generally, vacuum sensors either mechanically or electromechanically switch from an empty product container to a full product container by sensing the level of vacuum pulled on the empty product container. A disadvantage of sensing vacuum levels, however, is that an in-line device is necessary to determine if a vacuum level is low. An in-line device, such as a vacuum sensor, can come in contact with the beverage and create contamination issues.
Another issue with prior art beverage dispensing machines involves splattering during the initiation of dispensing. With some nozzle designs, there may be a problem during the opening or closing of the nozzle, especially when the opening or closing is performed slowly. As the nozzle plunger lifts into the nozzle body, breaking the nozzle seal and allowing product to flow through the newly-created gap, the flow may disassociate and splatter as it dispenses in a non-uniform fashion. When the nozzle becomes fully open, the flow generally returns to a smooth and uniform flow.
Another issue with prior art beverage dispensing machines it that prior art machines have been unable to provide precise mixtures of various dairy products, for example, milk, cream, and water. While mixing dairy products is used in the large scale commercial production of dairy goods, an ability to mix dairy products on the fly in a dispensing machine has not been introduced in dairy dispensing machines. One of the difficulties in providing dairy mixtures is that precisely controlling the ratios of dairy products is difficult to achieve with gravity flow dairy dispensing devices, and also machines that dispense individual servings. Another difficulty involves mixing different products in a manner that is not apparent to the user.
Yet another issue with beverage dispensing systems pertains to tracking the amount of remaining product left in the machine that is available for dispensing. Beverage dispensers may employ both direct and indirect methods to determine the amount of product remaining.
Indirect methods of determining the remaining quantity of product include counting the number of cycles a pump turns to expel a product and counting the time during which the dispensing valve is open. With the pump cycle count method, if the amount of material dispensed for each pump cycle is known as well as the initial amount of ingredient prior to pumping, the remaining ingredient amount can be calculated. In the time count method, the remaining ingredient amount can be calculated if the flow rate and the initial ingredient amount are known. Indirect methods of determining remaining product quantity, however are prone to error because of inaccuracies in flow rate assumptions and inaccuracies in initial product volume.
A direct method of measuring remaining product quantity, on the other hand, weighs the ingredient container using a load cell or pressure sensor. The product container might rest on a shelf integrated with a sensor, or it might sit directly on a sensor. A disadvantage of this method is that the sensing system or portions of the sensing system sit below the ingredient container. Since food ingredient containers need to be washable, any sensor that sits below an ingredient container may be prone to issues relating to cleaning, sanitation, and difficulties caused by spilling or leaking ingredients. Another problem with the load cell approach is that the product package is usually attached to the product cavity whose volume is being measured. Since the product package is weighed along with the product inside it, measuring inaccuracies may result.
Another direct method of measuring product volume is to put measuring devices in-line with product flow. Vacuum, pressure, or conductivity can be sensed in-line to determine when the product bag is empty. A disadvantage of the in-line sensing method is that it requires measuring devices that come in physical contact with the product. This is a potential source of contamination that requires proper cleaning and sanitation.